# UNDF: UNDF-2026-000000957
--- a/source/simulation2/components/CCmpRangeManager.cpp
+++ b/source/simulation2/components/CCmpRangeManager.cpp
@@ -1,6 +1,8 @@
 // CWE-407: CCmpRangeManager m_ModifiedEntities uses std::vector with std::find
 // for dedup. RequestVisibilityUpdate is called per-entity, and GetLosVisibility
 // scans the vector per-entity per-player. With E entities and M modified,
 // this is O(E*M) per frame. Fix: use std::unordered_set for O(1) membership test.
+#include <unordered_set>

 // --- Declaration change ---
@@ -409,7 +411,7 @@
-	std::vector<entity_id_t> m_ModifiedEntities;
+	std::unordered_set<entity_id_t> m_ModifiedEntities;

 // --- Serialization: convert set to vector for serialization ---
@@ -488,7 +490,10 @@
-		Serializer(serialize, "modified entities", m_ModifiedEntities);
+		// Serialize as vector for backward compatibility
+		std::vector<entity_id_t> modifiedVec(m_ModifiedEntities.begin(), m_ModifiedEntities.end());
+		Serializer(serialize, "modified entities", modifiedVec);
+		// On deserialize, rebuild set from vector
+		if (!serialize)
+			m_ModifiedEntities = std::unordered_set<entity_id_t>(modifiedVec.begin(), modifiedVec.end());

 // --- GetLosVisibility: O(1) lookup instead of O(M) ---
@@ -1777,7 +1782,7 @@
-		if (std::find(m_ModifiedEntities.begin(), m_ModifiedEntities.end(), entId) != m_ModifiedEntities.end())
+		if (m_ModifiedEntities.count(entId))
 			return ComputeLosVisibility(ent, player);

 // --- UpdateVisibilityData: iterate set, pop via iterator ---
@@ -1877,8 +1882,11 @@
 		while (!m_ModifiedEntities.empty())
 		{
-			entity_id_t ent = m_ModifiedEntities.back();
-			m_ModifiedEntities.pop_back();
+			auto it = m_ModifiedEntities.begin();
+			entity_id_t ent = *it;
+			m_ModifiedEntities.erase(it);

 // --- RequestVisibilityUpdate: O(1) insert instead of O(M) find ---
@@ -1891,8 +1899,7 @@
-		if (std::find(m_ModifiedEntities.begin(), m_ModifiedEntities.end(), ent) == m_ModifiedEntities.end())
-			m_ModifiedEntities.push_back(ent);
+		m_ModifiedEntities.insert(ent);
 	}